Leslie!!!

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S: Skeletal System!!

FC: Skeletal System!!

1: SKELETAL SYSTEM | By: LESLIE BLANKENSHIP

2: The skeletal system is composed of bones; connective tissues such as tendons, ligaments and cartilage; and teeth.

3: Humans are born with more than 300 bones in our bodies. Over time, though, some of these bones fuse together, leaving us with 206 individual bones at adulthood. | Bones have an outer layer of dense, firm compact bone and an inner layer of more flexible spongy bone. Some bones also contain bone marrow in the interior of the spongy bone, which produces cells for the bloodstream | The longest bone, the femur in the leg, provides about one fourth of a person's height. The smallest bone, the stirrup, is buried deep inside the ear and is barely the size of a grain of rice.

4: Your spine is one part of the skeleton that's easy to check out: Reach around to the center of your back and you'll feel its bumps under your fingers. The spine lets you twist and bend, and it holds your body upright. It also protects the spinal cord, a large bundle of nerves that sends information from your brain to the rest of your body. The spine is special because it isn't made of one or even two bones: It's made of 26 bones in all! These bones are called vertebrae (say: ver-tuh-bray) and each one is shaped like a ring.

5: When you were a baby, you had tiny hands, tiny feet, and tiny everything! Slowly, as you grew older, everything became a bit bigger, including your bones. | If you've ever seen a real skeleton or fossil in a museum, you might think that all bones are dead. Although bones in museums are dry, hard, or crumbly, the bones in your body are different. The bones that make up your skeleton are all very much alive, growing and changing all the time like other parts of your body.

6: Your spine is one part of the skeleton that's easy to check out: Reach around to the center of your back and you'll feel its bumps under your fingers. The spine lets you twist and bend, and it holds your body upright. It also protects the spinal cord, a large bundle of nerves that sends information from your brain to the rest of your body. The spine is special because it isn't made of one or even two bones: It's made of 26 bones in all! These bones are called vertebrae (say: ver-tuh-bray) and each one is shaped like a ring. | Spine!

7: In between each vertebra (the name for just one of the vertebrae) are small disks made of cartilage. These disks keep the vertebrae from rubbing against one another, and they also act as your spine's natural shock absorbers. When you jump in the air, or twist while slamming a dunk, the disks give your vertebrae the cushioning they need.

8: Your heart, lungs, and liver are all very important, and luckily you've got ribs to keep them safe. Ribs act like a cage of bones around your chest. It's easy to feel the bottom of this cage by running your fingers along the sides and front of your body, a few inches below your heart. If you breathe in deeply, you can easily feel your ribs right in the front of your body, too. Some thin kids can even see a few of their ribs right through their skin. | RIBS!!

9: Your ribs come in pairs, and the left and right sides of each pair are exactly the same. Most people have 12 pairs of ribs, but some people are born with one or more extra ribs, and some people might have one pair less.

10: Your skull protects the most important part of all, the brain. You can feel your skull by pushing on your head, especially in the back a few inches above your neck. The skull is actually made up of different bones. Some of these bones protect your brain, whereas others make up the structure of your face. If you touch beneath your eyes, you can feel the ridge of the bone that forms the hole where your eye sits. | SCULL!!

11: Your skull is pretty cool, but it's changed since you were a baby. All babies are born with spaces between the bones in their skulls. This allows the bones to move, close up, and even overlap as the baby goes through the birth canal. As the baby grows, the space between the bones slowly closes up and disappears, and special joints called sutures connect the bones.

12: As you sit and type at the keyboard, while you swing on a swing, even when you pick up your lunch, you're using the bones in your fingers, hand, wrist, and arm. | The center part of your hand is made up of five separate bones. Each finger on your hand has three bones, except for your thumb, which has two. So between your wrists, hands, and all your fingers, you've got a grand total of 54 bones — all ready to help you grasp things, write your name, pick up the phone, or throw a softball!

13: Each of these bones is wider at the ends and skinnier in the middle, to help give it strength where it meets another bone. At the end of the radius and ulna are eight smaller bones that make up your wrist. Although these bones are small, they can really move! Twist your wrist around or wave and you'll see how the wrist can move. | HAND!!

14: Sure, your arm, wrist, hand, and finger bones are great for picking up the phone, but how are you supposed to run to answer it? Well, with the bones of the legs and feet! | Your legs are attached to a circular group of bones called your pelvis. The pelvis is a bowl-shaped structure that supports the spine. It is made up of the two large hip bones in front, and behind are the sacrum and the coccyx. The pelvis acts as a tough ring of protection around parts of the digestive system, parts of the urinary system, and parts of the reproductive system. | LEGS!!

15: Most people don't use their toes and feet for grabbing stuff or writing, but they do use them for two very important things: standing and walking. Without all the bones of the foot working together, it would be impossible to balance properly. The bones in the feet are arranged so the foot is almost flat and a bit wide, to help you stay upright. So the next time you're walking, be sure to look down and thank those toes!

16: The place where two bones meet is called a joint. Some joints move and others don't. Fixed joints are fixed in place and don't move at all. Your skull has some of these joints (called sutures, remember?), which close up the bones of the skull in a young person's head. One of these joints is called the parieto-temporal suture — it's the one that runs along the side of the skull. | JOINTS!!

17: Another important type of moving joint is the ball and socket joint. You can find these joints at your shoulders and hips. They are made up of the round end of one bone fitting into a small cup-like area of another bone. Ball and socket joints allow for lots of movement in every direction. Make sure you've got lots of room, and try swinging your arms all over the place. | Have you ever seen someone put oil on a hinge to make it work easier or stop squeaking? Well, your joints come with their own special fluid called synovial fluid that helps them move freely. Bones are held together at the joints by ligaments , which are like very strong rubber bands.

18: Protect those skull bones (and your brain inside!) by wearing a helmet for bike riding and other sports. When you use a skateboard, in-line skates, or a scooter, be sure to add wrist supports and elbow and knee pads. Your bones in these places will thank you if you have a fall! | If you play sports like football, soccer, lacrosse, or ice hockey, always wear all the right equipment. And never play on a trampoline. Many kids end up with broken bones from jumping on them. Broken bones can eventually heal, but it takes a long time and isn't much fun while you wait. | Keep bones HEALTHY!!

19: Strengthen your skeleton by drinking milk and eating other dairy products (like low-fat cheese or frozen yogurt). They all contain calcium, which helps bones harden and become strong. | Be active! Another way to strengthen your bones is through exercise like running, jumping, dancing, and playing sports. Take these steps to be good to your bones, and they will treat you right!